1206 CAKDUACEAE 



49. FSILACTIS A. Gray. 



Annual caulescent herbs, glandular, pubescent or glabrate. Leaves alternate, various, 

 those of the basal or lower stem-leaves with pinnatifid blades ; those of the upper leaves 

 often entire. Heads radiate. Involucres hemispheric : bracts in 2-3 series, wholly her- 

 baceous or with herbaceous tips. Eeceptacle flattish. Kay-flowers pistillate in a single 

 series. Disk-flowers more numerous that those of the ray, perfect. Stigmas with puberu- 

 lent or hispidulous appendages. Achenes narrow, pubescent, those of the ray sometimes 

 with a mere ring representing the pappus, those of the disk with a single series of short 

 hair-like bristles. 



1. Psilactis asteroides A. Gray. Stems 3-10 dm. tall, scabrous-puberulent, or 

 glabrate, branching above : leaf-blades 1-7 cm. long, narrowly spatulate and toothed at 

 the base of the stem, oblong or linear and entire above : involucres 3 mm. high, becoming 

 rather flat at maturity ; bracts oblong to linear : ray-flowers with linear ligules 4-5 mm. 

 long : achenes 2 mm. long, minutely pubescent. 



In dry soil, Texas to Arizona and adjacent Mexico. 



50. SERICOCARPUS Nees. 



Perennial caulescent herbs. Leaves alternate : blades various, entire or toothed. 

 Heads radiate, in corymbs. Involucres ovoid to campanulate or cylindric, several-flow- 

 ered : bracts leathery, in few series, with erect or spreading tips. Receptacle naked, pitted. 

 Bay-flowers pistillate, with white or pink ligules. Disk-flowers chiefly perfect, with yel- 

 lowish or purplish corollas. Anthers entire and obtuse at the base. Style-branches with 

 narrow appendages. Achenes flattened, 1-nerved on each side. Pappus of numerous 

 scabrous bristles, the inner ones longer. 



Leaf-blades entire. 



Foliage glabrous or nearly so. 1. S. linijolius. 

 Foliage manifestly pubescent. 



Bracts of the involucres obtuse, firm : peduncles rigid, stout. 2. S. bifoliatus. 



Bracts of the involucres acute, lax : peduncles weak, slender. 3. S. acutisquamotus. 



Leaf-blades toothed. 4. S. aster&ideg. 



1. SericocarpuB linifolius (L.) B.S.P. Stems often tufted, 2-7 dm. tall, glabrous 

 or nearly so. Leaf-blades spatulate or linear-spatulate at the base of the stem to linear 

 above, 2-6 cm. long, entire, sessile or short-petioled : involucres narrowly cylindric, 5-7 

 mm. high ; bracts ovate-oblong, to linear-oblong, obtuse, often with erose green tips : ray- 

 flowers with linear involute ligules : pappus whitish, copious. [ solidagineus Nees.] 



In sandy soil, Canada, south to Georgia. Ohio and Louisiana. Summer and fall. 



2. Sericocarpus bifoliatus (Walt.) Porter. Stems cinereous-pubescent, 3-7 dm. 

 tall, sometimes branched below. Leaf-blades spatulate to obovate, 1-3 cm. long, obtuse or 

 apiculate, vertical, sessile : involucres about 6 mm. high, cylindric ; bracts ovate to linear- 

 oblong, obtuse, sometimes minutely pubescent : pappus white, copious. [ tortifolius 

 Nees.] 



In dry sandy pine lands, Virgina to Florida and Louisiana. Summer and fall. 



3. Sericocarpus acutisquamosus (Nash) Small. Similar to S. bifoliatus in habit, 

 but less robust. Leaf -blades oblong-spatulate, 1-3.5 cm. long, rather weak, acutish or 

 apiculate, entire, scabrous, sessile : involucres narrowly cylindric or cylindric-turbinate, 

 6.7 mm. high ; bracts narrowly linear-lanceolate, acute, the outer ones rather densely pu- 

 bescent : pappus white, copious. [$. bifoliatus acutisquamosus Nash. ] 



In pine lands, peninsular Florida. Summer. 



4. Sericocarpus asteroides (L.) B.S.P. Stems 3-8 dm. tall, glabrous at least ta 

 the sometimes viscid-pubescent peduncles. Leaf-blades 4-15 cm. long, toothed, those of 

 the basal and lower stem-leaves spatulate, oblong or oval, those of the upper stem- 

 leaves broadest at or above the middle or sometimes lanceolate : involucres 6-9 mm. 

 high, cylindric or oblong-cylindric ; bracts ovate to linear, with appressed or spreading 

 green tips : ray-flowers with whitish ligules 6-8 mm. long. [S. conyzoides Nees.] 



In rocky woods, Maine to Ohio, south to Florida to Alabama. Summer. 



51. ASTER L. 1 



Perennial branching glabrous or pubescent herbs, various in habit, but seldom annual, 

 unbranched, shrubby or spinescent. Leaves alternate : blades broad or narrow, often en- 



1 Contributed by Professor Edward S. Burgess. 



